Disk drive mapping out data tracks to avoid thermal asperities

Abstract

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of data tracks, wherein the head comprises a write element and a read element. An asperity in a target data track is detected, and a range of data tracks proximate the target data track is mapped out, wherein the range of data tracks spans at least twice a radial offset between the read element and the write element at the radial location of the target data track.

Description

BACKGROUNDDescription of the Related Art[0001]Disk drives comprise a disk and a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk. The disk comprises a plurality of radially spaced, concentric tracks for recording user data sectors and embedded servo sectors. The embedded servo sectors comprise head positioning information (e.g., a track ID) which is read by the head and processed by a servo controller to control the velocity of the actuator arm as it seeks from track to track.[0002]FIG. 1 shows a prior art format of a disk 2 comprising a plurality of concentric servo tracks 4 defined by embedded servo sectors 60-6N. Each servo sector (e.g., servo sector 64) comprises a preamble 8 for synchronizing gain control and timing recovery, a sync mark 10 for synchronizing to a data field 12 comprising the coarse head positioning information (such as a Gray coded track ID), and servo bursts...

AI Technical Summary

Benefits of technology

The patent describes a new format for a disk drive that includes a head actuated over a disk. The head has a read element and a write element that are offset radially. The format also includes a plurality of servo tracks that help position the head accurately over the disk. The technical effect of this new format is that it reduces the likelihood of damage to the head and improves performance and reliability of the disk drive.

Problems solved by technology

An asperity may manifest on the disk surface due to a manufacturing defect of the disk, contaminates such as dust particles, friction particles due to the head sliding along a load / unload ramp, etc.

If the head strikes an asperity, it can raise the temperature of the head (thus the term thermal asperity) resulting in unreliable write / read performance as well as physically damage to the head.

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